Research On The Effect Of Central Clamp On Suspension Bridge

introductionSuspension bridges have the advantage of large spanning capacity,light structure,beautiful appearance,etc.They are the preferred type for long-span bridges.Suspenders are the main component that transmit the force between the girder and the main cables.Safety and durability of its components are very important to the structure.However,through many field inspections for different suspension bridges,the short hangers at the mid-span show some damages under the cyclic traffic loads.These damages are frequently observed at the lower ends of short suspenders.To accurately anticipate the causes of the damages and the influence of central clamp on short hangers on the structural performance,a detailed analysis is conducted for Jiangyin Yangtze River Bridge as a study case in this paper.The main contents are as follows:(1)Based on previous investigations and researches on the damage of the main cables and suspenders of suspension bridges either in China or abroad,it is found that damages of the short hangers may be caused by the large repeated longitudinal displacement in the middle of the span,resulting in a large secondary Bending stresses.(2)Using the finite element software Midas to calculate and analyze the internal force of the real bridge of the Jiangyin Yangtze River Bridge,the internal force and stress of the hangers under different vehicle loads are obtained.Through the comparative analysis of whether the bridge has a central clamp,it is obtained that the central buckle can significantly reduce the stress of the hangers.(3)The finite element software Abaqus is used to calculate and analyze the displacement of the Jiangyin Yangtze River Bridge to obtain the internal force and displacement of the hangers under different vehicle loads.By analyzing the internal force of the short hangers in different positions of the vehicle,the most unfavorable position of the vehicle that affects the stress of the short suspenders is obtained.By comparing the obtained results with the actual monitoring data of the bridge,the theoretical simulation is in good agreement with the field results.Through the comparative analysis of whether the bridge has a central clamp,the influence of the central clamp on the displacement of the hangers and the performance of the entire bridge is obtained.(4)Finally,through the refined analysis of the secondary bending stress of a single short suspender,the variation range of the short suspender’s secondary bending stress under five different end displacements is compared and analyzed.Studies have shown that the maximum secondary bending stress of the short hangers may exceed the fatigue load of the hanger,resulting in cracking.However,if the bridge uses a central clamp,the secondary bending stress of the hangers will be significantly reduced.Based on the results of stress analysis,the stress magnification factors of the secondary bending of the short suspender caused by live load are put forward under the two working conditions of the bridge with or without central clamp,which recommended to be used in the actual calculation and analysis of the short suspenders.